Stool to be used in the casting of metal



Nov. 23, 1937. c. H. ALDRICH STOOL TO BE USED IN THE CASTING OF METALFiled (Jet. 22, 1935 INVENTOR Patented Nov. 23, 1937 UNITED STATESPATENT OFFICE Charles H. Aldrich, Elizabeth, N. J., assignor to TheAmerican Metal Company; Limited, New York, N. Y., a corporation of NewYork Application October 22, 1935, Serial No. 46,096

.8 Claims.

geal therein, whereupon the mold is removed and again used. In carryingout the casting process it has been found that the poured metal tends tocut away parts of the mold, and that the tremendous amount of heat whichis released by the molten ingot frequently results in a cracking of themold surfaces. Usually it is the bottom of the mold which gives wayfirst. Consequently, in the past, it has been the practice to form thebottom' of the mold separately from the side portions thereof, wherebythe bottom, or stool as it is called, may be replaced when it becomesworn.

In the past several diflerent types of stools have been proposed. One ofthe earliest of these was made of a solid block of cast iron; Thismetal, as is well known, has a relatively low coefiicient of heatconductivity, and consequently the heat of the poured metal was unevenlyand rather slowly distributed therethrough, and dissipated there- .from.In other words, the heat tended to concentrate at that point, or in thatarea, against which-the stream of molten metal first impinged .as it waspoured into the mold. Now, uneven heating results in uneven expansion;and where one part expands more than another then the metal will buckleor crack. Accordingly, after a relatively short period of time, thesecast iron stools became so covered with cracks as to be of no furtheruse.

Later it was proposed to build the stool from a solid block of copperwhich, having a much greater coefficient of heat conductivity, wouldtend to distribute the heat of the casting morerapidly and more evenly.This expedient was relatively satisfactory, and such stools had a fargreater life than the prior cast iron one. However, in time the streamof molten metal would begin to cut and erode the surface, and further,cracks and fissures eventually appeared.

In both of the foregoing typesof stool considerable trouble was causedby the tendency of the poured metal to weld itself to the stool. This,as can readily be understood, resulted in a very considerable loss oftime in separating the ingot from the stool, and further, it tended tocontaminate the metal of the ingot.

The principal object of the present invention is to overcome thesedifliculties and thereby to lengthen the useful life of the stool. Thisgenerally is done by subdividing the stool into a plurality of componentparts which are yieldingly pressed together so that they may expand andcontract independently one of another whereby opposed expansionalstresses are avoided; and by utilizing different materials in differentparts of the stool to counteract different destroying forces. The latterfeature is accomplished by making that portion of the stool againstwhich the molten metal first strikes, termed the area ofdirect-impingement from a material which will resist to a maximum degreethe cutting action of the stream of molten metal and which is of suchcharacter as not to become welded to the ingot; I and by making theremaining portion of the stool, termed the area of non-impingemen from amaterial which will distribute the heat evenly and rapidlytherethroughout.

Other objects and various features of the invention willbe more apparentfrom the following description to be read in connection withtheaccompanying drawing, in which Figure 1 is a plan view of a stoolwhich incorporates the principles of my invention;

Fig. 2 is a cross-sectional view taken along the line 2-2 of Fig. 1; V

Fig. 3 is a fragmentary cross-sectional view of a stool embodying myinvention and showing a modified form thereof;

Fig. 4 is a similar view of another modification of the invention;

Fig. 5 is a fragmentary plan view of a stool in which either of themodifications of Fig. 3 or 4 may be included. Y

' One embodiment of the invention, as'shown in Fig. 1, comprises aplurality of relatively narrow bars II and I2 which are disposed in sideby side relation and mounted upon a suitable bed l3. As can be seen, thebars are of a length somewhat less than the width of the bed.Consequently, any expansion lengthwise of the bar will not be opposed bythe sides of the bed; that is, the bars are free to move in thatdirection. Further, the bars are yieldingly pressed together in suchmanner that any expansion crosswise thereof may be absorbed by theyielding means. Accordingly, each bar may expand in this -directionindependently of every other bar. Thus, as will be apparent from theforegoing, the component parts of the stool are free to adjustthemselves in any direction whereby opposed expansional andcontractional forces are completely avoided.

When molten metal is poured into a mold mounted upon such a stool itwill usually strike the latter at one point or within a relatively smallarea and then flow over the remaining portions thereof. After the stoolhas been used a number of times it will be found that this area ofdirect impingement has become corroded to a very marked extent; and thatthe ingot tends to weld itself to this area. In other words, the streamof molten metal tends to cut away the part of the stool against which itstrikes, and then to weld itself thereto. The extent of these effectswill be found to differ with the character of metal which is being cast.Thus, in general, high carbon steel and certain alloys have a greatertendency to cut the stool and to become welded thereto than do lowcarbon steels and other alloys. Accordingly, the bars II whichconstitute the area of direct inpingement are preferably made ofamaterial which will oppose these tendencies to a maximum degree. Inpractice, it has been found that cast iron and certain alloys willresist these destructive effects when certain types of metal are beingcast, while in other cases such refractory materials as carbon,graphite, carborundum, fire clay, magnesite, chromite and the like, mustbe used. Thus, the material which is to constitute the area .of directimpingement will be selected in accordance with the character of themetal which is to be cast. The remaining bars I2 constituting the areaof non-impingement are preferably made from copper, or other materialhaving a comparatively high coefficient of heat conductivity.

Inindividual cases it will be found that the area of direct impingementmay constitute a greater, or lesser, proportion of the total area of thestool; and a greater, or lesser, proportion of the total depth thereof;and the arrangement" of this area may be varied in several ways. In Fig.3, for example, the direct impingement bars Ila are only approximatelyhalf as deep as the adjoining bars l2, and they are underlaid by anequal number of bars [211 which preferably are formed of the same metalas the bars l2. Further, these bars may extend the total width of thestool, as is illustrated in Fig. 1, or they may be fore-shortened, as isshown in Fig. 5. In the latter case the area of direct impingement willbe substantially surrounded by the bars constituting the area ofnon-impingement; that is, it will be adjoined on both sides by bars l2,on the ends by bars I25, and it will be underlaid by bars I211; 1

Another variation is shown in Fig. 4, in which the area of directimpingement may constitute a solid block of the desired material; andthis block may extend the full depth of the stool, or it may be in alesser proportion. Further, it may extend the full width of the stool orit may be foreshortened in a manner similar to that illustrated in Fig.5.

Considering the advantages of the stool as a whole it will be seen thatthe composite character permits a selection of those materials whichwill best counteract the destructive effects of the molten metal. Thus,the bars II which are intended to resist cutting and welding may bechosen in accordance with the character of the metal which is to becast; and the bars l2 may be made from a metal which will evenly andrapidly distribute the heat of casting. The laminated character of thestool not only avoids cracking, as hereinbefore described, but itpermits an easy and rapid change of the character of the area of directimpingement.

Each of the foregoing features tends to lengthen the effective life ofthe stool. Accordingly, in practice, it will be found that thiscomposite type stool has a considerably longer normal life than anythingheretofore proposed. Further, such a stool may be very readily andinexpensively repaired. Thus, the laminated construction makesreplacement of worn bars a relatively simple matter; and the inexpensivecharacter of the area of direct impingement, wherein most wear occurs,permits replacement of this area at a very small cost.

Since certain changes may be made in the embodiment of the inventionwithout in any way departing from the true scope thereof, it is intendedthat the foregoing shall be construed in a descriptive rather than in alimiting sense.

What I claim is:

1. A composite stool for an open bottomed ingot mold having an area ofdirect impingement formed from a material which is highly resistant tothe corrosive action of a stream of poured molten metal, and an area ofnon-impingement formed from metal having a high coefficient of heattransfer whereby it may rapidly and evenly distribute heatthroughout theentire stool, both the area of direct impingement and the area ofnon-impingement being formed from bars which are disposed in side byside relation, and the stool being further characterized in that thearea of direct impingement is underlaid by a portion of the area ofnon-impingement.

2. A composite stool for an open bottomed ingot mold having an area ofdirect impingement formed from a plurality of relatively narrow bars ofcast iron which is adapted to resist the corrosive action of a stream ofpoured molten metal, and an area of non-impingement adjoining the areaof direct impingement, the area of nonimpingement comprising a pluralityof relatively narrow copper bars disposed in side by side relation andadapted to distribute the heat of the cast ingot rapidly and evenlythroughout the entire stool.

3. A composite stool for an open bottomed ingot mold comprising aplurality of relatively narrow bars disposed in side by side relationwith the side surface of one bar in contact with the side surface of theadjacent bar so that their tops form substantially a continuous surfaceupon which an ingot may be cast, certain of the bars constituting thatportion of the stool against which a stream of poured metal would bemost likely to strike being formed from a material which is adapted toresist the corrosive action of such a stream, the

constituting that portion of the stool against which a stream of moltenmetal would be most likely to strike are made of cast iron.

6. A composite stool for an open-bottomed ingot mold having an area ofdirect impingement comprising a plurality of bars of metal highlyresistant to the corrosive action of a stream of poured molten metal,and an area of non-impingement comprising a plurality of bars of metalhaving a high heat transfer coeificient whereby it may rapidly andevenly distribute heat throughout the entire stool, the stool beingfurther characterized in that all of the bars are disposed in side byside relation, and that the bars comprising the area of directimpingement are underlaid and adjoined on two sides by the barsconstituting the area of non-impingement.

7. A composite stool for an open-bottomed ingot mold having an area ofdirect impingement comprising a plurality of bars of metal highly resistant to the corrosive action of a stream of poured molten metal, and anarea of non-impingement comprising a plurality of bars of metal having ahigh heat transfer coefficient whereby it may rapidly and evenlydistribute heat throughout the entire stool, the stool being furthercharacterized in that all of the bars are disposed in side by siderelation, and that the bars comprising the area of direct impingementare underlaid and surrounded by the bars constituting the area ofnon-impingement.

8. A composite stool for an open-bottomed ingot mold, comprising aplurality of relatively narrow bars of substantially identical size andshape disposed in side by side relation with the side surface of one barin contact with the side surface of an adjacent one, so that their topsform substantially a continuous surface upon which an ingot may be cast,the middle bars constituting that surface against which a stream ofpoured molten metal will first impinge being formed from cast iron so asto resist the corrosive action of such molten stream, and the remainingbars constituting the end surfaces being formed of copper so as todistribute the heat of casting rapidly and evenly throughout the stool,the cast iron bars being of substantially the same depth as the copperones.

CHARLES H. ALDRICH.

